The present invention relates to a process to manufacture, in a laboratory and/or on industrial scale, mineral or synthetic or silicone lubricant greases, in which hydrophilic or hydrophobic silicon dioxide (fumed silica) or precipitated and ground silicic acid are mixed with mineral oils or vegetable oils or synthetic esters or silicone oils or glycerine or propylene glycol at relatively low temperature and pressure, including atmospheric pressures. As a result, the control of the mixture as well as the control of the thickening or polymerization reaction are facilitated. The polymerization or thickening reaction may be carried out in a short time relative to existing processes for the manufacture of metallic soap lubricant greases such as sodium, calcium, lithium, magnesium, aluminum and polyurea lubricant greases, in which the saponification or polymerization reaction is carried out at high pressures and temperatures in a considerably greater time, involving high manufacturing costs.
In the prior art, there are some processes that use silicon dioxide as a thickener, such as the process described in U.S. Pat. No. 4,378,297 in which lubricant sealers which are resistant to solvents such as chloroform and carbon disulfide are prepared by forming a grease comprising glycerine, hydrophobic fumed silica, polyethylene glycol and a minor amount of water.
U.S. Pat. No. 4,701,272 discloses a silicone grease composition containing methylphenyl polysiloxane having a specific surface area of at least 130 m/.sup.2 /g, and an alkoxy containing organosiloxane compound. Likewise, South African Patent No. 86/0555 discloses a grease containing a suitable polypropylene glycol, a thickener comprising finely particulate silicon and an extreme pressure functional additive.
However, the greases obtained from these mentioned processes have limited characteristics.